Process in which cellulose acetate artificial silk and like products are treated with hot liquors



Patented June'Ze, 1930 UNITED STATES PAKI'ENTZ OFF-ICE.-

ABCHIBALD JOHN HALL, OI TIMBEBSBROOK, GONGLE'ION, ENGLAND, 'ABSIGNOB IOGELANESE CORPORATION OF AMERICA, GQRPOBATION OI DELAWARE rnocnss mwnrcrrcnnnunosn ACETATE ARTIFICIAL srnx AND 1.11m rnonuo'rs' ABE TREATEDWITH nor LIQUORS 1T0 Drawing. Application liled July 22, 1925, SerialNo. 45,418, and in Great Britain July 81, 19.

This invention relates to'the treatment of cellulose acetate productswith hot or boiling aqueous liquors.

It is Well known that when cellulose acetre, appearance and transparencywhen heated at about 100 C. for prolonged periods in an aqueous solutioncontaining not lessthan a minimum quantity of a suitable protectivesubstance. Many salts, chiefly-neutral salts, have been found capable ofacting as protective substances but the important fact which we haveestablished is that their protective action is dependent on theirconcentration in the aqueous solution in which they are employed;

Generally, the protective power of suitable salts is greater inconcentrated aqueous solutions than in dilute solutions. For example,cellulose acetate silk becomes Woolly and opaque and loses most of itslustre when heated for three minutes in boiling water, but

1 retains its original appearance and properties when heated for onehour at about 100 C. in an aqueous solution containing 12% of sodiumchloride or 25% of crystalline sodium sulphate. On the other hand,cellulose acetate silk similarly heated for one hour at about 100 C. inan aqueous solution containing 5% of sodium chloride becomes somewhatwoolly and suffers a partial loss of lustre and transparency.

It is necessary, therefore, that the concentration of the salt solutionsused must be above a certain minimum, varying with the salt or mixtureof salts employed,in order to ensure complete protection of the lustre.For convenience the minimum concentration at which any particularprotective saline agent, Whether said saline agent be a single salt or amixture of salts, must be employed in order to prevent any loss oflustre is hereinafter termed its critical protective concentration.

The following substances have been found to act as protective substancestowards cel-- lulose acetate artificial silk Substance Ammonium bromide.Ammonium chloride. Ammonium chromate. Ammonium oxalate. Ammoniumsulphate. Alum. Sodium bichromate. Sodium sulphite.

Sodium phosphate (dibasic). Sodium nitrite.

Sodium bisulphite. Sodium acetate. Sodium thiosulphate. Sodiumferrocyanide. Sodium chlorate. Sodium nitrate. Sodium bromide. Calciumchloride. Cadmium chloride. Copper sulphate. Chrome alum. Ferrousammonium sulphate. Strontium chloride. Potassium chromate. Potassiumferrocyanide. Zinc sulphate.

Tartar emetic.

Ferrous sulphate.

Zinc chloride. Potassium sulphate. Iron alum.

Barium chloride. Magnesium chloride. Magnesium sulphate. Potassiumchloride. Sodium chloride. Sodium sulphate. Sodium hydrosulphite-Aluminium chloride. Sodium sulphite. Ortho-aminophenol-para-sulphonicacid. Ammonium nitrate. Ammonium phosphate. Potassium sulphlte.Potassium nitrate. Potassium oxalate.

centration are only stated ap roximately and the following table gives te approximate value of concentration for several of the substances.

Approximate concentration of aqueous solution in which protection ofcellulose acetate is evident Substance v Ammonium chloride 50 grams in100 cc. of water Sodium sulphate 5 Sodium chloride 10 Magnesium sulphate10 Magnesium chloride 10 Calcium chloride 10 Sodium phosphate Potassiumsulphate- 20 Barium chloride 20 Strontium chloride 20 Ammonium bromide10 Aluminium chloride 20 Potassium chromate 20 Sodium sul hite 20 Sodiumhy rosulphite 20 Our discovery of the protective action of protectivesubstances for cellulose acetate silk is important since it enables thistextile material to be immersed in or otherwise treated with aqueoussolutions at higher temperatures than has hitherto been possible in suchpresence of water at temperatures in excess of about 85 0., comprisingeffecting the treatment in the presence of an aqueous solutioncontaining between about 10% and about 30% of a neutral ammonium salt.

In testimony whereof I have hereunto subscribed my name. ARGHIBALD JOHNHALL.

operations as bleachingirscouring, dyeing,

printing and steaming. urther, union fabrics containing celluloseacetate silk may be treated without injury to the silk with such hot orboiling liquors as is desirable for the purpose. of scouring, dyeing orotherwise treating the other fibres present in the fabric, for examplecotton, linen, wool or silk.

Among numerous processes in which our discovery has useful applicationsis the dyein in boiling liquors of fabrics containing cefiulose acetateand woollen fibres, the dischargin of dyed cellulose acetate fabrics inboiling iquors and the relief or production of latent strains incellulose aoetatefabrics or products by immersion in a boiling aqueousliquor.

What I claim and desire to secure by Letters Patent is 1. Process forpreventing loss of lustre in bleaching, dyeing, printing, steaming andotherwise treating textile materials, films and other materialscomprising cellulose acetate at temperatures in excess of about 85 0.,

- characterised in that the treatment is effected in the presence of aprotective saline agent comprismg a neutral ammonium salt in an aqueoussolution of a concentration efi'ective to maintain thelustre of saidmaterials.

2. Process for preventin loss of lustre in treating textile materials,ms and other materials, comprising cellulose acetate in the

